This invention relates to implements attached to vehicles, and especially to implements which interact with the ground, or with a softer media on the ground.
The "ground" as used herein refers to natural soil surfaces, compacted soil surfaces; and artificial surfaces harder than natural soil surfaces, such as concrete and asphalt, and the like.
A "media" as referred to herein means any bulk or aggregate matter which can be moved, or otherwise acted upon, by the power available at the vehicle on which the implement is mounted. Typical of softer media is snow, sand, gravel, loose dirt, and the like. It is contemplated that the invention can also be applied in working with harder media such as virgin soil, coal, blasted stone, breccia, debris, and the like.
In preferred embodiments, the invention relates to plows and the like for moving snow. Accordingly, the invention is described herein with respect to snow plows, and moving snow with such plows.
Those skilled in the art will see that the invention herein can apply to other implements, and for interacting with, and working, media other than snow. Exemplary of such media are gravel, stones, dirt and the like.
Snow is commonly moved using trucks having a front mounted plow blade. Such plows normally are attached to the trucks, under the truck chassis, and near the front wheels, with a pair of attaching pins.
Typically the plow blade is lifted off the ground by a chain, one end of which is attached to the plow frame; and the other end of which is attached to a lift arm pivotally mounted on the truck. The lift arm is powered by a single-acting hydraulic cylinder/ram connected to the truck and to a portion of the lift arm remote from the truck. When the ram is powered, the lift arm is lifted, lifting the chain and, respectively, the plow blade. When the power is released from the ram, the weight of the plow blade takes it down to the ground. Accordingly, the effective weight at the edge of the plow blade is governed by the weight/mass, and the distribution of the weight/mass, of the plow.
If the snow is light, the weight, and typical shape, of the plow blade, are effective for moving the snow. If, however, the snow has been compacted, the weight of the plow is sometimes not sufficient to break up the compacted snow, whereby a compacted surface of snow is left on the ground after plowing. This is especially true of plows used on smaller trucks, such as pick-up trucks.
Another problem related to conventional snow plows mounted on trucks is related to driving the truck with the plow raised. The plow is typically raised when it is not being used for plowing, such as when traveling to a work site, or between jobs. In such cases, the plow is raised by lifting on the chain, and is held in the raised position while the truck is driven about, or to the next job site, or the like. At any rate, trucks having snow plows thereon are commonly driven from place-to-place with the plows raised, and held up by the chains.
While so traveling, when the truck hits a bump the plow can be thrown up by the force of the bump, enough that the chain is momentarily slack. When the plow comes back down, the momentum of the plow is suddenly absorbed by the chain as a shock, and transferred to the vehicle. Such a shock is hard on the vehicle suspension. It is also disruptive to control the vehicle, and so may be dangerous. Finally, when the plow is thrown up, and the chain is slack, it is possible for the chain to come loose from the lift arm of the truck, whereupon the plow impacts the road or ground unintentionally, causing severe handling of the vehicle.
It is an object of this invention to provide an implement interface which is adapted to apply a downwardly directed force to the implement, sufficient to enable an operator to adjust the effective operation of the implement.
It is another object of this invention to provide an interface which provides solid support of the lifted implement.
It is still another object of the invention to provide an interface wherein the resistance to throwing of the implement upwardly increases proportionate to upward travel of the implement from the lifted position.
It is yet another object to provide an interface wherein a force throwing the implement upwardly is counteracted by a compression spring on the interface, and wherein the spring is necessarily under compression at all conditions of operation of the interface.
Still another objective is to provide means and a method to apply a downwardly directed force on the working surface of the implement.